<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        span {
            /*margin-top: ;*/
            /*行内元素的垂直方向无法设置内外边距*/
            /*    需要设置使用行高调整 line-height*/
        }

        span:first-child {

        }

        span:last-child {

        }

        span:nth-child(5) {

        }

        span:nth-last-child(5) {

        }
    </style>
</head>
<body>
<span>
    span

</span>
</body>
</html>